The present invention relates to the field of airjet spinning machines. Airjet spinning machines have a multiplicity of spinning stations. In each spinning station, a yarn is spun from a longitudinal fiber structure. In this case, the longitudinal fiber structure is first refined by drafting, a process in which the fiber quantity per unit length is reduced. The refined fiber composite is then spun into a yarn by imparting a twist.
Yarn breaks, of course, cannot be prevented and result in an interruption of the spinning process. To resume the spinning process, the free yarn end which results from the yarn break is drawn out opposite to the spinning direction (upstream) beyond the twist-imparting point and is positioned. The initial region of the fiber composite, which overlaps the free yarn end after the free yarn end is positioned, is subsequently connected to the free yarn end by imparting a twist in the spinneret. The spinning operation is thus resumed.
The thread take-off duct, also called a yarn duct or spindle duct, must have specific dimensions for spinning and structural reasons. The length L of the spindle duct has a value in the range of about 60 mm to 80 mm. The diameter dE of the entry orifice of the spindle duct has a value in the range of about 0.8 mm to 1.2 mm. The diameter dA of the exit orifice of the spindle duct has a value of about 2.0 mm or less. The diameter dA of the exit orifice of the spindle duct typically has a value that is greater than the value of the diameter dE of the entry orifice of the take-off duct. The above mentioned dimensions of the spindle duct define a thin and long bore. Because of these dimensions, the operation of guiding the free yarn end back in the spindle duct is very awkward.
A known method and device for repiecing provides an ejector duct through which compressed air is injected for the reintroduction of the yarn. This results in an injection air stream acting “upstream.” A spinning device which includes an injector duct is also disclosed in which, by the admission of compressed air, the thread take-off duct can be moved away in order to make it easier to reintroduce the yarn. However, the arrangement of these aforementioned injector ducts has not yet led to fully satisfactory results.
An object of the present invention is to provide a method and a spindle for carrying out the method, which, after an interruption in a spinning process, allow the yarn to be guided back reliably and accurately to produce a piecer. The spindle for carrying out the method is to have a simple configuration in structural terms.